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PNGenie - lossless PNG optimiser for Mac OS X

Background

A PNG file contains image related data. This data can be stored in a multitude of different ways and the file size will vary for each storage method—even with the same raw image data. Image files often have an attached resource fork that also artificially increases the size of the file.

Purpose

PNGenie optimises any given PNG file—trying out different methods of compression—with a goal of achieving the smallest file size. Smaller files are good for a number of number practical reasons as well as, obviously, saving disk space. Let's say you want to reduce the size of data files belonging to an iPhone application, or you want to speed up loading of a website that uses PNG images, for example. Resource forks, gamma values and software-specific tags are automatically stripped, too.

Download

Installation

Copy PNGenie.app to your Applications folder.

Optionally, place a shortcut in your Dock for easy access.

First Usage

Upon first run—for licencing reasons—you will be asked if you wish to download PNGOUT, an additional program that will result in increased optimisation.
If you choose to do so it will be downloaded and stored within PNGenie. If you wish to change your mind, you will need to delete PNGenie and download it again.

General Usage

Drag one or more PNG files onto the application. Running the application normally with a double click will bring up a file selector. PNG files larger than about 50kb may take a while to optimise, just in case you think the app is not responding.

Case Study

I took a sample of 1,000 small PNG files—all previously optimised using other methods. Their combined file size before PNGenie was 3.4MB and combined file size after PNGenie is 0.54MB!

Troubleshooting

Photoshop and Internet Explorer can have trouble opening a small percentage of files that have been processed by PNGenie. If this is the case, simply open the PNG in question using Preview, or similar, and re-save it.

Version History

28 July: looks for more recent version of pngout (1.40)
07 March: looks for more recent version of pngout (1.30)
2011
25 January: looks for more recent version of pngout (1.20)
2010
20 July: Added file selector if app is launched through double click rather than drag and drop. Final compatibility fix for Intel Macs (1.10)
14 July: Compatibility fix for 32-bit Intel Macs. Also displays an alert if you launch without using drag and drop (1.01)
3 July: Initial release (1.00)
2009